Personally, I don't disassemble anything to clean except for the tap itself. I clean a keg, then mix a couple of quarts of cleaner in it and hook it up as I would a brew. Hit it with just a little gas, enough to get a bit of positive pressure. No need to waste CO2 by fully pressurizing a nearly empty keg. Then dispense until it comes out "all cleaner" and let it sit for a 1/2 hour or so in the lines. Then dispense the remainder of the cleaner. Rinse the keg well, leave a bit of clean water in it and hook it up and dispense to rinse the lines. Then I may mix a little sanitizer and run it through the lines just for a piece of mind. If I won't be using that tap right away, I leave the sanitizer in the lines and push it out with the beer when I get another brew online.
I don't clean my lines but every 3rd or 4th keg change myself. Some like to clean at every change.